[HTML-AAM] effect of CSS display and tabindex on <span>

Something that has been bugging me is the effect of CSS display properties
on elements that are normally not represented in the acc tree

http://s.codepen.io/stevef/debug/mJJOKq?

in the example above, depending on the browser (checked only
IE/Firefox/chrome on windows) changing the CSS display value of a span, or
adding a tabindex=0 may change its role(s) reported via APIs, add it to the
acc tree or do nothing,
(note: chrome adds in seemingly random Ia2_section/divs to output).

There is no uniformity of behaviour across browsers.

Part of the issue (i think) is that expected behaviour is not defined
anywhere.
and think it should be defined:
effect of CSS display properties
effect of tabindex.


I think that the disparities would cause issues for AT using the acc APIs,
but am happy to be told otherwise.

comments?





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Regards

SteveF
HTML 5.1 <http://www.w3.org/html/wg/drafts/html/master/>